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Port 4335 (netconf-ch-tls)

IANA assigns port 4335 to netconf-ch-tls: NETCONF Call Home (TLS).

Registered (user) port, 1024-49151 TCP

IANA assignment

Service nameProtoDescriptionAssigneeReference
netconf-ch-tls TCP NETCONF Call Home (TLS) IESG RFC 8071

Registry dates for this port: registered 2016-01-12.

Check what is listening on port 4335

Linux: is anything listening on TCP 4335?
sudo ss -tlnp 'sport = :4335'
Linux / macOS: which process owns the port
sudo lsof -nP -i :4335
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':4335 '
Windows (Command Prompt)
netstat -ano | findstr :4335
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 4335 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 4335
From Windows
Test-NetConnection HOST -Port 4335

Block port 4335 in the firewall

ufw
sudo ufw deny 4335/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 4335 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 4335 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 4335' -Direction Inbound -Protocol TCP -LocalPort 4335 -Action Block

Related ports

4333ahsp4334netconf-ch-ssh4336restconf-ch-tls4340gaia

All port numbers · Open port checker
Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.